Submission #3990

#	Time	Username	Problem	Language	Result	Execution time	Memory
3990		cki86201	Following Flow (kriii1_F)	C++98	0 / 1	0 ms	1100 KiB

F

#include<stdio.h>

struct edge{
	int st,en,len;
};
edge data[1005];
long double t[2][35],p[2][35];
long double cnt[35];
int n,m;

int main()
{
	long double ans=0;
	int s=0, e=1, ct=0;
	scanf("%d%d",&n,&m);
	for(int i=0;i<m;i++){
		scanf("%d%d%d",&data[i].st,&data[i].en,&data[i].len);
		cnt[data[i].st]++;
	}
	p[s][0]=1;
	while(1){
		int i;
		for(i=0;i<n;i++){
			if(p[s][i]>1e-30&&t[s][i]>1e-30)break;
		}
		if(i==n)break;
		for(int i=0;i<=n;i++)p[e][i]=t[e][i]=0;
		for(int i=0;i<m;i++){
			p[e][data[i].en]+=p[s][data[i].st]/cnt[data[i].st];
			t[e][data[i].en]+=(t[s][data[i].st]+data[i].len*p[s][data[i].st])/cnt[data[i].st];
		}
		ans+=t[e][n];
		s=!s; e=!e;
	}
	printf("%.9lf",ans);
}
/*
#include<stdlib.h>
int main()
{
	freopen("input.txt","w",stdout);
	for(int i=0;i<1000;i++){
		printf("%d %d 50\n",rand()%30,rand()%30);
	}
}*/

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